chromeos: adds TouchDeviceServer and wires up in mushrome

services/ui/public/interfaces/input_devices/BUILD.gn

 # Copyright 2016 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import("//mojo/public/tools/bindings/mojom.gni")
 
 mojom("input_devices") {
   sources = [
     "input_device_server.mojom",
   ]
 
   public_deps = [
     "//ui/events/devices/mojo",
   ]
+
+  if (is_chromeos) {
+    sources += [ "touch_device_server.mojom" ]
+    public_deps += [ "//ui/display/manager/chromeos/mojo:interfaces" ]
+  }
 }